Sevgen Onder
Hacettepe University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Sevgen Onder.
Pattern Recognition | 2012
Aslı Gençtav; Selim Aksoy; Sevgen Onder
The Pap smear test is a manual screening procedure that is used to detect precancerous changes in cervical cells based on color and shape properties of their nuclei and cytoplasms. Automating this procedure is still an open problem due to the complexities of cell structures. In this paper, we propose an unsupervised approach for the segmentation and classification of cervical cells. The segmentation process involves automatic thresholding to separate the cell regions from the background, a multi-scale hierarchical segmentation algorithm to partition these regions based on homogeneity and circularity, and a binary classifier to finalize the separation of nuclei from cytoplasm within the cell regions. Classification is posed as a grouping problem by ranking the cells based on their feature characteristics modeling abnormality degrees. The proposed procedure constructs a tree using hierarchical clustering, and then arranges the cells in a linear order by using an optimal leaf ordering algorithm that maximizes the similarity of adjacent leaves without any requirement for training examples or parameter adjustment. Performance evaluation using two data sets show the effectiveness of the proposed approach in images having inconsistent staining, poor contrast, and overlapping cells.
Pathology Research and Practice | 2003
Figen Soylemezoglu; Sevgen Onder; Gaye Guler Tezel; Mustafa Berker
The use of neuronal nuclear antigen (NeuN) as a reliable neuronal marker in the differential diagnosis of clear cell neoplasms of the central nervous system was determined in a biopsy series of 23 cases. Immunohistochemical analyses were carried out by antisera against neuronal nuclear antigen, synaptophysin, neuron-specific enolase, microtubule-associated protein 2, and glial fibrillary acidic protein. All eight central neurocytomas were characteristically immunolabeled by NeuN. NeuN immunoreactivity was uniformly strong and basically located in the nuclei of neurocytes. Despite this uniform staining pattern of central neurocytomas, 12 cases of oligodendrogliomas and three cases of ependymoma were negative for NeuN. As the diagnostic criteria for central neurocytoma include immunohistochemical and/or ultrastructural evidence for neuronal differentiation, NeuN as a sensitive and specific neuronal marker in formalin-fixed, paraffin-embedded tissues may greatly facilitate the differential diagnosis of central neurocytomas.
CytoJournal | 2015
Anders Hjerpe; Valeria Ascoli; Carlos W.M. Bedrossian; Mathilde E. Boon; Jenette Creaney; Ben Davidson; Annika Dejmek; Katalin Dobra; Ambrogio Fassina; Andrew Field; Pinar Firat; Toshiaki Kamei; Tadao K. Kobayashi; Claire W. Michael; Sevgen Onder; Amanda Segal; Philippe Vielh
To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma (MM). Cytopathologists involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC), who have an interest in the field contributed to this update. Reference material includes peer-reviewed publications and textbooks. This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists, who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in cape town. During the previous IMIG biennial meetings, thorough discussions have resulted in published guidelines for the pathologic diagnosis of MM. However, previous recommendations have stated that the diagnosis of MM should be based on histological material only.[12] Accumulating evidence now indicates that the cytological diagnosis of MM supported by ancillary techniques is as reliable as that based on histopathology, although the sensitivity with cytology may be somewhat lower.[345] Recognizing that noninvasive diagnostic modalities benefit both the patient and the health system, future recommendations should include cytology as an accepted method for the diagnosis of this malignancy.[67] The article describes the consensus of opinions of the authors on how cytology together with ancillary testing can be used to establish a reliable diagnosis of MM.
Cytopathology | 2014
Sevgen Onder; Pinar Firat; D. Ates
In this study, we investigated the efficacy of the Bethesda system (TBS) for reporting thyroid cytopathology in determining the risk of malignancy for indeterminate cases. These cases comprised atypia or follicular lesion of undetermined significance (AUS/FLUS), follicular neoplasia or suspicious for follicular neoplasia (FN/SFN) and suspicious for malignancy (SM) categories. AUS/FLUS cases were further subcategorized according to their patterns, and the malignancy rate for each subcategory was calculated.
Acta Cytologica | 2015
Anders Hjerpe; Valeria Ascoli; Carlos W.M. Bedrossian; Mathilde E. Boon; Jenette Creaney; Ben Davidson; Annika Dejmek; Katalin Dobra; Ambrogio Fassina; Andrew Field; Pinar Firat; Toshiaki Kamei; Tadao K. Kobayashi; Claire W. Michael; Sevgen Onder; Amanda Segal; Philippe Vielh
Objective: To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma. Data Sources: Cytopathologists with an interest in the field involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC) contributed to this update. Reference material includes peer-reviewed publications and textbooks. Rationale: This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in Cape Town.
Apmis | 2011
Aysegul Uner; Nalan Akyürek; Arzu Saglam; Samir Abdullazade; Nuket Uzum; Sevgen Onder; Ibrahim Barista; Mustafa Benekli
Uner A, Akyurek N, Saglam A, Abdullazade S, Uzum N, Onder S, Barista I, Benekli M. The presence of Epstein–Barr virus (EBV) in diffuse large B‐cell lymphomas (DLBCLs) in Turkey: special emphasis on ‘EBV‐positive DLBCL of the elderly’. APMIS 2011; 119: 309–16.
Journal of Breast Cancer | 2012
Aysegul Oz; Figen Başaran Demirkazık; Meltem Gulsun Akpinar; Isıl Soygur; Atac Baykal; Sevgen Onder; Aysegul Uner
Purpose We performed this study to detect preoperative axillary metastases with ultrasound (US)-guided fine needle aspiration biopsy (FNAB), to eliminate the need for time-consuming and costly sentinel lymph node (SLN) scintigraphy and biopsy steps in the treatment of breast cancer patients, and in that of with suspicious US findings, and to evaluate the accuracy of preoperative US-guided FNAB for patients with suspicious lymph node metastases on US. Methods Patients with a suspicious breast lump or histopathologically proven breast cancer underwent breast-axillary US. Increase in lymph node size, cortical thickening, non-hilar cortical flow, and hilar changes were evaluated with gray scale-color Doppler US. FNAB was performed if US results were suspicious for malignancy. Results Thirty-eight axillary lymph nodes (ALN) underwent FNAB. ALN dissection, SLN scintigraphy, and biopsy steps were bypassed in 23 axillas with positive ALN FNAB (60.5%). The sensitivity of ALN FNAB was 88.46%; specificity and positive predictive value were 100%; and negative predictive value was 66.6% (inadequate cytology included; 76.7%, 100%, 100%, 53.3%, respectively). Asymmetrical cortical thickening, non-hilar cortical flow, and increase in hypoechogenity were only detected in metastatic nodes. Cortical thickening, and lymph node and breast mass size was higher in the metastatic group. Conclusion By performing FNAB on suspicious lymph nodes, the routine, high-cost SLN scintigraphy and intraoperative gamma probe steps may be skipped, and axilla dissection can be performed directly. This leads to the elimination of the need for SLN investigation in more than half of the patients. The assessment of ALN metastases with preoperative US-guided FNAB is a cost-effective method with high specificity, that eliminates the need for costly and time-consuming SLN scintigraphy and biopsy steps, and helps in preoperative staging.
Diagnostic Cytopathology | 2015
Anders Hjerpe; Valeria Ascoli; Carlos W.M. Bedrossian; Mathilde E. Boon; Jenette Creaney; Ben Davidson; Annika Dejmek; Katalin Dobra; Ambrogio Fassina; Andrew Field; Pinar Firat; Toshiaki Kamei; Tadao K. Kobayashi; Claire W. Michael; Sevgen Onder; Amanda Segal; Philippe Vielh
To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma.
Clinical and Experimental Ophthalmology | 2008
Hayyam Kiratli; Sevgen Onder; Sibel Yıldız; Havva Solak Ozseker
A 30‐year‐old woman complained of right‐sided epiphora for 2 years. She also reported diplopia on certain gaze positions and felt a hard mass behind the right medial inferior orbital rim. Magnetic resonance imaging studies demonstrated a relatively well‐delineated mass in the right inferomedial orbit with minimal ethmoid sinus involvement. Histopathological evaluation following a large incisional biopsy showed massive eosinophilic infiltration and fibrosis with the final diagnosis of eosinophilic angiocentric fibrosis. She was then discovered to have significant peripheral eosinophilia and elevated serum IgE levels and clinical findings of allergic rhinitis and sinusitis. She was treated with systemic fluorocortolon and desloratadin for 4 months. She remained stable without recurrence for 32 months. The patient with this exceptionally rare tumour of the orbit benefited from debulking surgery followed by systemic corticosteroids and antihistaminics.
Cytopathology | 2007
Pinar Firat; Canan Ersöz; Aysun Uguz; Sevgen Onder
Objective: To investigate the accuracy of fine needle aspiration cytology (FNAC) in the diagnosis of cystic masses of the head and neck (H&N), excluding thyroid lesions.